Latch pivot die



June 5, 1934. I A FER T 1,961,430

LATCH PIVOT DIE Original Filed June 15, 1931 Patented June 5, 1934 LATCH PIVOT DIE Ali Ferret, Iorrington, Torrington Company,

Conn., assignor to The Torrington, Conn., a corporation of Connecticut Original application June 15, 1931, Serial No.

544,670. Divided and this application December 14, 1933, Serial No. 702,392

2 Claims.

This application is a division of my application for method of making latch needles filed June 15, 1931, Ser. No. 544,670, allowed November 7, 1933,

. and relates to the tools utilized for carrying out such method.

Said method in detail consists in making of a knitting machine needle blank with a slot to receive a latch, forming the latch with a pivot hole,

inserting said latch into the needle slot, exerting an initial pressure upon the walls of the needle slot, over the pivot hole and over a smaller surface area than the cross section of the pivot hole in the latch to form opposite trunnions in face contact in said pivot hole and exerting a final pressure upon the walls of the needle slot and over a larger surface area than the cross section of the pivot hole in the latch to cause radial enlargement of the trunnions to fill the hole and form a solid pivot, said final pressure being exerted along a convex surface to clamp the walls of the needle slot and prevent their bulging.

The tool which forms the subject matter of this application comprises a pair of axially movable dies or presser members which are simultaneously actuated to engage the opposite walls of the needle slot and press portions of them toward each other to form two oppositely disposed pivot members which are forced into the pivot hole in axial alinement with each other.

The invention is illustrated in the accompanying drawing in which- Fig. 1 represent a somewhat enlarged view of a completed needle constructed according to my method.

Figure 2 and 3 are greatly enlarged views partly diagrammatic showing the prior art dimpling operation, Fig. 3 illustrating how the sides of the needle have been reduced by milling.

Fig. 4 is a section similar to Figs. 2 and 3 showing the needle constructed in accordance with my method.

Fig. 5 represents an enlarged view of the two opposite dies or presser members which form the subject matter of the present invention, and

Fig. 6 is a detail view showing more clearly the shape of the tenon and the end of the die, the small figure at the left being a projection of the tenon.

In the drawing, and referring particularly to Fig. 4, 1 represents the latch to be applied to the needle 2, and 3 is the opening in the latch. Into this latch opening the trunnions 4 and 5 are pressed from opposite sides by the use of the dies 3 which form indentations 6 and 7, the metal displaced by extrusion from the points 6 and 7 passing into the opening in the latch until the two inwardly displaced trunnions abut against each other and cause an outward flow of the metal to form a substantially cylindrical bearing for the latch. The sides 8 and 9 of the needle are left in the original full size condition giving the needle exceptional smoothness and full strength.

In Figs. 2 and 3 is illustrated the prior art construction of the needle made with so-called dimpling punches, 10 and 11 illustrating the metal raised up by the ordinary punch and forcing the metal 12 and 13 into the hole in the latch, as shown in Fig. 2. This raised metal 10 and 11 must be removed by some means of grinding or cutting, as shown at 17V in Fig. 3, thus greatly weakening the needle and causing sharpness and roughness at the edges which of course is objectionable in its action on the yarn in the knitting operation.

The tool for carrying out the method shown and described and claimed in the parent application above referred to is illustrated particularly in Figs. 5 and 6. The shank portion of the tool is represented at 14. 15 are punches or tenons which are of less cross sectional area than the cross sectional area of the pivot hole in the latch, and these tenons 15 form the indentations 6 and 7 when forced into the sides of the needle and make the initial abutting trunnions. Each tool is formed with convex shoulders, as shown at 16, adjacent the tenons 15, and the entire surface of the end of each tool is of greater cross sectional area than the cross sectional area of the pivot hole.

By reason of the convexity of the shoulders 16 adjacent the tenons the pressure of the dies or presser members causes an outward flow of the initially formed trunnions so that the hole in the pivot latch is completely filled, as shown at 4 and 5 in Fig. 4, and such convexity of the tools prevents any lateral fiowing or bulging of the metal of the sides of the needle and causes the needle to retain its normal surface contour and diameter so that no material has to be removed but the needle is kept at its full diameter and strength. These convex portionsalso act after the tenons have performed their initial function, to clamp the needle while causing the initial flow, to obviate the bulging of the sides thereof.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A die or presser member for forming the pivot for a latch needle, comprising a shank portion of greater cross sectional area than the cross sectional area of the pivot hole in the latch, and

7 tional area of the pivot hole in the latch, and a tenon of less cross sectional area than the cross sectional area of the pivot hole formed in the latch, the shoulders on the shank adjacent the tenon being convex in form whereby progressive pressure of the shank portion is exerted on the sides of the needle after the initial pressure of the tenon has formed the trunnion to cause a lateral enlargement of the trunnion and prevents bulging of the side of the needle.

ALI FERRET. 

